Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: The Prophet (peace and blessings be upon him) used to say this supplication after the tashahhud: "O Allah, I seek refuge with You from the punishment of Hell, I seek refuge with You from the punishment of the grave, I seek refuge with You from the trial of the Dajjal, and I seek refuge with You from the trials of life and death."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10893